The goal of this study was to assess starch degradability, protein fractionation, and fermentation profile of wet brewers grain (WBG) ensiled with maize or sorghum grains. Two treatments were prepared: maize + WBG, maize rehydrated with WBG; and sorghum + WBG, sorghum rehydrated with WBG, with 10 replications per treatment, adjusted to 55% dry matter (DM). Data were analysed in a completely randomized design using the MIXED procedure of SAS. Losses and pH were lower in maize + WBG, however, it also presented higher lactic acid bacteria, yeasts, moulds, and lactic acid (P < 0.001). Acetic acid did not differ; but propionic acid was lower in maize + WBG. The DM and EE were higher in maize + WBG, whereas ash, neutral detergent fibre, acid detergent fibre, and crude protein were lower in this treatment. Starch concentration was similar, however with higher degradability in maize + WBG. The A1, A2, and C protein fractions were higher for maize + WBG; while B1 and B2 were lower. Overall, WBG ensiled with maize showed higher A1 (ammonia) and A2 (soluble protein) protein fractions, and higher starch degradability compared with sorghum silages rehydrated with WBG.